An exposed photographic film is known to be subjected to photographic processing baths, such as for example for developing, fixing and washing with water in the case of a radiographic film, and is then dried to remove the impregnating water after processing.
It is also known that this drying process is a critical stage in the entire photographic process, to the extent that it influences the quality of the final image obtained. It can be carried out either inside drying chambers into which high temperature air is blown, or by passing the film through them if they are provided with and conveying means which are normally disposed at least partially inside the chambers themselves. These conveying means generally consist of rollers which rotate about their axis and which by rotating cause a film in contact with them to move along the conveying plane determined by the points of contact between said rollers and the film. In particular, said rollers can be disposed in series either opposing or offset, as described for example in U.S. Pat. No. 3,025,779.
A conveying device of the second type generally includes a fan which blows air towards a heat source and then on to both the faces of the film to be dried while it passes through the drying chamber. The hot air flow dries the film more rapidly the higher the temperature of the air blown on to the film (the hot air source being either a conventional electric heating element or a different heat source such as an infra-red ray source as described in British Pat. No. 1,131,681). Temperature of said hot air is normally at 50.degree. to 70.degree. C.
Alternatively, such devices include infra-red radiation sources, placed close to the film so as to directly irradiate it with infra-red rays, combined with non-heated air, the flow of which is induced by fan means and both cools the film and takes away the moisture evaporated from the film, as described in U.S. Pat. No. 3,900,959.
It is considered that the second aforesaid type of device represents an advancement in the art of drying a water-impregnated photographic film, but it is also considered that a further advance can be made to attain a drying device which adds efficiency and smoothness of operation, as well as processing latitude, to operational economy.